Device for maintaining the tension in the warp threads of a loom uniform



Dec. 8, 1953 w KRETZSCHMAR 2,661,774

DEVICE FOR MAINTAINING THE TENSION IN THE WARP THREADS OF A LOOM UNIFORMFiled May 3, 1951 4 Sheets-Sheet 1 7 INVENTOR. GEORGE w. mzrzscm/ueATTOQMEKB Dec. 8, 1953 G. w. KRETZSCHMAR 2,661,774

7 DEVICE FOR MAINTAINING THE TENSION IN THE WARP THREADS OF A LOOMUNIFORM Filed May 3, 1951 4 Sheets-Sheet 2 INVENTOR. 6501265 PV. IZQETZSCHMAB OLJNL,

A 7' TOQNE Y5 Dec. 8, 1953 s. w. KRETZSCHMAR 2,661,774

DEVICE FOR MAINTAINING THE TENSION IN THE WARP THREADS OF A LOOM UNIFORMFiled May 3, 1951 4 SheecQs-Sheet 3 Fig.5

' I "III'I'I'II" INVENTOR. 69 79 650.426;- w. KAETZSCHMAIQ ysybwkfglwATZ'OQNEYS G. W. KRETZSCHMAR DEVICE FOR MAINTAINING THE TENSION IN I THEWARP THREADS OF A LOOM UNIFORM 4 Sheets-Sheet 4 IN V EN TOR.

m m E M N H R C O n W m A K mv M Dec. 8, 1953 Filed May 3, 1951 in-1. 52u f n} u llll l I Patented Dec. 8, 1953 DEVICE FOR MAINTAINING THETENSION IN THE WARP THREADS OF A LOOM UNI- FORM George W. Kretzschmar,Ridgewood, N. J. Application May 3, 1951, Serial No. 224,357

9 Claims.

This invention relates to looms and, more particularly, to a device forletting off the warp from a warp beam under an initial tension which hasbeen preset for the particular quality of the goods to be woven.

In applicants copending application, Serial Number 181,663, filed August26, 1950, there was illustrated and described a tension unit for lettingoff the warp from the beam under uniform tension regardless of thediameter, width, or weight of the beam. In the tension unit there wasalso illustrated and described in detail a full floating whip rolleragainst each end of which a hydraulically deflected compression springexerts an equal pressure regardless of the out of horizontal position ofone end of the roller relative to the other. The tension unit isdesigned to prevent or to eliminate in a woven cloth defects from sideto side which arise from uneven tension across the warp or any portionthereof. Subsequently it was found desirable to include a new visiblemeans for determining the average amount of spring deflection orpressure on the ends of the floating whip roller. It was also founddesirable to transmit the up and down or reciprocal movement of the whiproller from an average position thereon to a control arm actuating asignal light and to incorporate in the control arm means for adjustingthe let off from the warp beam with the loom in motion. It was also ifound desirable to provide means in coaction with the control arm forletting off the warp from the warp beam with each and every stroke(pick) of the loom in approximately the exact amount required for eachstroke or pick, and means for releasing all the tension or for Varyingthe tension on the warp of a loom at rest.

It is an object of the instant invention to provide a device which willlet off the warp under uniform tension regardless of the diameter,width, or weight of the warp beam.

A further object is to provide a device for maintaining a uniformtension in the warp threads during the entire letting oif of the warpfrom a full beam to an empty one.

Another object is to provide a floating whip roller against each end ofwhich a hydraulically deflected compression spring exerts an equalpressure, regardless of the position (up or down) of either end, topress the whip roller against the warp at any position thereof withequal pressure and to impart therein uniform tension.

Still another object is to transpose the motion from an average positionof the tension imparting mechanism to a control arm for actuating asignal light and for guiding a control rod the position of whichdetermines the amount of let off.

It is also an object of the instant invention to provide means forletting off the warp from a warp beam with each and every stroke of theloom (pick) and approximately in the exact amount required for eachpick. I

An additional object is to provide means to signal with a light wheneverthe tension on the warp changes within presetlimits whether the loom bein operation or at rest.

Still another object is to provide a visible graduated scale for readingthe average amount of spring deflection against the whip roller in thetension unit or the tension on the warp.

t is moreover an object of the instant invention to provide means formanually releasing all tension on the warp on a loom at rest.

A further object is to provide means on a loom at rest for manuallyincreasing or decreasing the warp tension when the warp has stretched orshrunk and without interfering with the preset spring pressure.

Other objects of the instant invention will become apparent in thecourse of the following specification.

In the attainment of these objectives, the desired tension in the warpis maintained uniform by a tension unit, a warp beam let off mechanismin operable engagement with the tension unit, and a full floating warpbeam in operable engagement with the let ofi mechanism. The tension unitwas described in detail in the p=reviously mentioned copendingapplication, Serial Number 181,663, and is designed to let off the warpthread from a full to an empty beam under uniform tension. As describedin the copending application, the tension unit isconstituted in part ofa full floating whip roller under upwardly directed preset pressureagainst the warp for the quality of the goods to be woven, the pressurebeing attained by' hydraulically operated compression springs. In thecopending application, a pressure gauge in the hydraulic fluid lineprovides a means for reading the pressure of the fluid against pistonswhich deflect the springs. In subject application, new means have beenprovided for reading directly the pressure of'pre designed springsagainst the whip roller by the deflection of the springs. The tensionunit of subject application further differs from the unit in thecopending application by providing a means for transmitting threciprocal movements of the whip roller from the average position to aconi: trol arm in operable engagement with a signal light for indicatingthe variation of the tension beyond predetermined limits, the meansbeing also in operable engagement with the let off mechanism. The letoff mechanism for the warp thread is in operable engagement with boththe control arm and the lay leg or stroking mechanism of the loom andincorporates a multiple pawl mechanism for a very fine let ofi of thewarp. To even further maintain the tension in the warp uniform, there isemployed known full floating rotatable supports for the beam in operableengagement with the let oif mechanism.

The invention will appear more clearly from the following detaileddescription when taken in conjunction with the accompanying drawingsshowing by way of example the preferred embodiments of the inventiveconcept.

In the drawings:

Figure l is a side elevational view in part section of the tension unit,the mechanism for maintaining the tension roller of the tension unit under uniform pressure against the warp and the let-off mechanism;

Figure 2 is a front elevational view of the mechanism shown in Figure 1;

Figure 3 is a top view of the mechanism shown in Figure 1;

Figure 4 is an elevational view taken in the direction of 4-4 of Figure3;

Figure 5 is a sectional view along 55 of Figure 2;

Figure 6 is a sectional view along 6-6 of Figure 1;

Figure 7 is an enlarged fragmentary elevational view of the multiplepawls controlling the magnitude of the warp let off from the beam witheach pick;

Figure 8 is a fragmentary top plan view of the multiple pawls shown inFigure 7;

Figure 9 is an elevational view of one of the improved coversconstituting a part of the mechanism for maintaining both ends of thewhip roller of the tension unit under uniform pressure against the warp;

Figure 10 is a fragmentary perspective View of one end of the fullfloating warp beam;

Figure 11 is a fragmentary perspective View of the control arm of thetension unit for controlling the length of the warp let oif from thewarp beam, and for closing the circuit to an electric light when thetension variations in the warp exceed predetermined limits; and

Figure 12 is a diagrammatic view of the mechanism for maintaininguniform pressure on both ends of the full floating whip rollerirrespective of the out of horizontal position of the roller.

Referring now in greater detail to the drawings where like referencenumerals indicate like parts, reference numeral l0 indicates the warpstand, H the tension unit, l2 the warp beam, [3 the let off mechanismfor the warp beam, [4 the tension adjusting mechanism for the tensionunit, and 15 the tension signal light.

The warp stand i0 is located at the warp end of a loom (not shown) andis constituted of the spaced side members 16 and I! (Fig. 3) which aredesigned, when fastened to the end of the loom, to support the warp beamand the tension control devices in a manner hereinafter described. Anysuitable means may be used for attaching the side members to the end ofthe loom.

At the top of the stand I 9 is the tension unit H as most clearly shownin Figures 1, 2, 3, and 5. The tension unit H is constituted of thesimilar end housings I3 at the top of each side of the warp stand andabove the warp beam 12. Each end housing has spaced side and endmembers, a closed top, and an open bottom (Figs. 1 and. 2). Each housingfurther has formed through the side members, the aligned openings 23 and24 (Fig. 2) adjacent the outer end or front of the unit and similaraligned openings 21 and 28 equally spaced inwardly and upwardly from theopenings 23 and 24. In the aligned openings 23 and 24 are any suitablebearings as illustrated. Rotatably supported by the bearings in thealigned openings 23 and 24 of each housing is the shaft 29 which, inturn, is rotatably inserted through the tension roller 39. Rotatablysupporting the shaft 29 above the side members of the stand are thesimilar adjustable brackets! (Fig. 2), one on each side of each sidemember. Each bracket of each pair has formed therethrough near thebottom a similar longitudinal slot 22 (Fig, 1) through which likefasteners 2! are inserted as well as through a registered opening (notshown) in the side member between the brackets. In the ends of each pairof brackets extended above the stand are a pair of aligned Openings 25and 26 (Fig. 2) equipped with bearings for the rotatable support of theends of the shaft 29 when suitably aligned with the openings 23 and 24in each end housing. Rotatably inserted through the previously mentionedopenings 2'! and 28 in each end housing is the shaft 3| of the whiproller 32. The inwardly directed ends of each housing are securedtogether by a light flexible channel member or tie rod 33 (Figs. 1 and5) with the channel directed toward the tension roller 30 or otherwise.Any known means may be used for attaching the channel member to the endsof the housing. By the construction described, both rollers 30 and 32are rotatable and the whip roller '32 and the end housings l8 pivotalabout the shaft 29 of the tension roller within the limits of thehousings and the stops 29a (Fig. l) integrally formed with each endhousing and coacting with the adjustable brackets l9. Also by virtue ofthe construction described in detail in copending application, SerialNumber 181,663, when the warp is drawn over the tension and whip rollersfrom the warp beam, the angle formed by the whip roller with the tensionroller for any diameter of warp beam remains constant because of theparallelogram of forces.

Fastened to one end of the shaft 29 of the tension roller 30 by anysuitable means 20 is a control arm 34 (Fig. 3) which is extendedinwardly under the channel member or tie rod 33 (Fig. 5). As shownespecially in Figure 11, the control arm 34 terminates at the free endin an upturned portion which has on one side an integrally formedelectrical contact 34a. Transversely disposed through the contact 34aand adjustable therein relative thereto is another electrical contact35. Both contacts 34a and 35 may be designated as movable contacts.Coacting with the movable contacts is a stationary or third contact 36(Fig. 11) in the circuit of the signal light I 5, the circuit for whichis well known but not shown. Both the light and the third or stationarycontact are attached in a known manner to a side member of the stand andthe stationary contact may be made adjustable. On the side of the arm 34opposite the movable electrical contacts is a member or eye which hasinserted therein a ball joint 35b for the slidable insertion of thelater described sleeve 64 which regulates the magnitude of the let off.

To more evenly distribute the forces acting on the tension unit and tooperate the control arm 34, a compensating rigid brace 42 (Fig.3) hasbeen incorporated in the tension unit. The brace 42 is of U-shape asillustrated with the forwardly directed end extremities 43 and 44 of theside portions 43a and l-ia, respectively, attached to opposite ends ofthe shaft 29 of the tension roller 30. The side portions 43a and tea arethen extended rearwardly under the whip roller 32 with the integrallyformed bottom or horizontal portion 45 adjacent the channel member ortie rod 33 on the side of the roller 32 as further illustrated.Substantially at the center of the bottom portion 45 is a pin 45extended rearwardly and pivotally fitted into the flexible channelmember. By virtue of the described construction, the whip roller is fullfloating and one end may be tilted above the other without varying thepressure against the warp threads as later shown. As the warp beamdecreases in diameter, the movement of the pin 48 is gradually downward.

To maintain the hull floating whip roller 32 at a predetermined upwardlydirected uniform pressure against all of the warp, there was describedin applicants aforementioned copending application, Serial Number181,663, a visible and balanced tension control device in whichreciprocal pistons in operable engagement with springs in turn inoperable engagement with the ends of the whip roller regulate thepressure of the roller against the warp and maintain the tension thereinconstalnt, the pressure being preset in accordance with the quality ofthe goods to be woven. As illustrated in Figure 12, the constructionadopted involves a master cylinder 38 in operable engagement with thepistons 3? of the slave cylinders through the medium of a hydraulicfluid. Predesigned compression springs are disposed between the land ofthe piston and the ends of the shaft 3|. By turning the head of themaster cylinder 38 down into the cylinder the hydraulic fluid isexpelled simultaneously into both slave cylinders to give an equalpreselected pressure on both ends of the shaft. However, the shaft 3|will not always be in a horizontal position because of (l) defectivebeams and beam gudgeons; (2) uneven warping; (3) misalignment of thetake-up and whip rollers; (4) unbalanced action of the lay leg; (5) wearand tear on bearings, pivots, and

cranks; etc. However, irrespective of the out of horizontal position ofthe shaft 3! the pressure of the springs thereagainst will not varysince the forcing of the fluid out of the left hand slave cylinder shownin Figure 12 will in turn force the fluid into the right hand slavecylinder to keep the pressure constant, the master cylinder remainingunchanged. In subject application, the visible and balanced tensioncontrol device is identical with the mechanism described and illustratedin the copending application except that the cover or guide 37a (Fig. 9)for the pistons and springs have formed therein a longitudinal open ing39. Along one edge of the opening 39 is a graduated scale 40, graduatedin fractions of an inch or pounds of pressure and correlated with thespring deflection so that as the index line on mark i! on the land ofthe piston supporting one end of the spring moves along the scale, adirect reading of the pressure on the whip roller at each end isvisible.

In operable engagement with the control arm I 34 of the tension unit isthe let off mechanism l3 for the threads of the warp beam E2. The warpbeam let off mechanism is con tituted as follows: Through one of theside members of the warp stand I0 an opening 420/, (Fig. 2) is made andthrough the opening is a portion of a housing 43b attached in a knownmanner to the side member. Rotatably and horizontally inserted in thehousing and parallel to the axis of the warp beam isthe helical gearbushing 45a, the outer end of which is extended beyond the end of thehousing and externally threaded as shown in Figure 6. Threaded on theextended end of the bushing is the ratchet gear 4511. Through thebushing 45a is rotatably inserted the shaft 42', the ends of whichprotrude beyond the ends of the bushing. On the inner extended end ofthe shaft 4'! is keyed the spur gear 48 in operable engagement with thelater described vertical rack 6! which, in turn, is in operableengagement with the later described sleeve d4, reciprocally inserted inthe arm 34. Rotatably secured over the outer extended ends of both thebushing and the shaft 47 is the stroke lever 49 of inverted U-shape.Pivotally attached to one side of the inverted U-shaped leversubstantially adjacent the horizontal or upwardly positioned bottomportion and on the outside, is the stroke arm 50 (Figs. 2 and 7), theopposite end of the stroke arm being in operable engagement with the layleg or stroln'ng mechanism of the loom (not shown). In operableengagement with the stroke lever 49 is the pawl lever 5! secured to theshaft 4! and on which are pivotally mounted and forwardly extended overthe teeth of the ratchet gear 46a the multiple pawls 52, 53, and 54. Itwill be noted in Figure 8 especially that each pawl is of difierentlength so that the ratchet gear 46a may have a minimum number of teethwhich in any position of the gear teeth will engage at least onethereof. The length of the pawls is dependent upon the circular pitch ofthe teeth divided by the number of pawls, that is the pawl ofintermediate length (Fig. 8) is made shorter by one third of thecircular pitch than the pawl of greatest length and the pawl of shortestlength is shorter than the pawl of intermediate length by one-third ofthe circular pitch. Thus, by using multiple pawls the ratchet gear 360,can have teeth of sufficient body to withstand long wear while the letoif resulting from the rotation of the ratchet gear by the pawls can bemade very fine.

On the inner surface of the ratchet gear 45a is a pulley (Fig. 6) arounda part of which the brake band 56 is passed, One end of the band isanchored in the brake support 5'! (Fig. 1),.

which is a part of or attached to the side member H5. The opposite endof the band is held under tension by the pin 55! slidably insertedthrough a screw 58 threaded through the support 51 with the head of thepin held in spaced rela-- tionship with the head of the screw by thespring 50.

As aforementioned, the spur gear 43 keyed to the inner end of the shaft47 is in operable en gagement with the rack 6i maintained reciprocal ina vertical position in a slideway at the back of the housing (Fig. 5),One end of a rod 62 s pivotally attached to the top of the rack 5! byany suitable pin es. The rod is then extended upwardly from the rack forthreaded attachment in the bottom of the previously mentioned sleeve 64(Fig. 5). The sleeve 54 extends vertically through a ball joint 35?) inthe eye 65 on the control arm 3 and terminates in a knob at the topwhich when turned will move the rod and rack up or down to turn theshaft 41 and vary the spacing of the pawl lever 5i relative to thestroke lever 59 to control the magnitude of the thread let ofi from thewarp beam. It is to be noted that the stroke of lever 49 as actuated bythe arm 50 in operable engagement with the lay leg or stroking mechanismof the 100m is constant and that pawl lever 51 and spur gear 43 aresecured to the shaft 41. The rack 61 is in mesh with the gear 48 and ispivotally connected at the top to one end of the rod 62. The oppositeend of the rod 52 is threaded into the sleeve 54 so that it can be madelonger or shorter. The knob-like top of the sleeve 65 comes to rest onthe ball joint 35?) with each stroke of the loom. Thus, the length ofthe rod 52 can be varied to determine the position of the pawl lever iWhile the turning of the knob is a manual operation, it will be notedthat the control of the let off is also auto matic. For example, supposethe tension in the warp becomes sufficiently increased to pivot thetension unit it and the control arm 34 downwardly. In the loweredposition, the sleeve 6:; will drop downwardly also to a lower positionuntil stopped by the knob-like top thereof. In the lowered position ofthe sleeve E4, the spacing between the pawl lever ii and the strokelever 49 will be decreased so that the pawls 52, 53 and 54 will be movedto a position to let off more warp as shown in the following paragraphto restore the uniform tension.

By the previously described construction, the helical gear bushing ifiawill be rotated in one direction by the ratchet gear dta in turnoperated by the pawls in accordance with the required let off. On thebushing and in the housing 63b is the gear 55a in operable engagementwith a gear 65 turning with a. rotatably mounted worm and helical gearshaft 66 which is in operable engagement with the worm gear 58 attachedto the end of the warp beam 12 in a manner subsequently described. Oneend of the shaft 65 protruding through the housing terminates in asquare head fil for the releasable attachment of a manually operatedwrench or crank which is not shown.

Since warp beams as a rule are not mechanically perfect, the gudgeon 69at each end of the beam is rotatably supported by a self-aligningcoupling of known design. In brief, the gudgeon fi is fastened in theend of the warp beam in the usual manner and protrudes through the openend of a barrel Til (Fig. also fastened to the end of the warp beam.Secured to the inner surface of the barrel and also protruding throughthe open end thereof are two spaced lugs H and '12. Coacting with thelugs is a plate i3 having the inwardly directed slots is and '15 and theoutwardly directed protuberances I6 and 11. The protuberances l5 and 11coact with spaced slots 80 in the worm gear 68 in the rotation of thewarp beam while a ring "18 attached to the ends of the lugs holds theplate in position. The extremities of the gudgeons are supported by thefloating bushings 8i, Each bushing has an outer race 32 horizontallydisposed through each of the stand side members (Fig. 6) and in which itis attached by welding or the like. In the inner surface of the outerrace is a recess of arcuate cross section on either side of the verticalcenter line. An inner race 83 is attached on the end of the gudgeon, theinner race being enlarged on the outer surface to provide a surfacecoacting with the recess of the inner race. The self-aligning couplingpreviously described is designed for the end of the warp beam having theworm gear 68. It is to be understood, however, that there is aself-aligning coupling for both ends of the beam, but since the let-ofimecha nism is applied to only one end, the plate 13 for the opposite endmay be of more simple construction.

In operation:

With the tension adjusting devices assembled in the manner previouslydescribed, the tension adjusting mechanism I4 is set by the use of thegraduated scales of each slave cylinder to read the average amount ofspring deflection or tension in the warp required for the particularquality of the goods to be woven and is never changed during the entireletting oil of the warp. Where a plurality of looms are used for weavinggoods of the same quality, the deflection of the springs arehydraulically set to the same scale reading and the weaves will all havethe same warp tension. For a pickup, that is, the removal of the fillingthreads, the loom is stopped and all tension released on the warp byturning the square head Bl of the shaft 66 clockwise until the endhousings 29a are stopped by the adjustable brackets l9. To reset thetension to the operating warp tension, the pawls 52, 53, and 54 arelifted upwardly out of engagement with the teeth of the ratchet gear46a, and the shaft 66 turned counterclockwise until the signal light l5goes out which gives a simple and novel method for pickouts. The strokelever 49 has a constant stroke and pushes the pawl lever SI for a partof the constant stroke while the stroke of the pawl lever 51 isdetermined by the position of the knob-like top of the sleeve 64 restingon the ball joint 35b for operating the ratchet gear Mic with the pawls52, 53, and 54. To manually increase or decrease the warp tension,without changing the hydraulically preset spring pressure against thewhi roller, on a loom at rest, the pawls are lifted and the shaft 66 isturned counterclockwise until one of the movable contacts 34a and 35 isdisengaged from the stationary contact 36, as the case may be, and thesignal light [5 goes out when increasing the tension, and clockwiseuntil the signal light l5 goes out when decreasing the tension. In aloom either at rest or in motion, the signal light out means that thewarp is under the initial or exact tension to which the warp has beenset. In a loom in motion, the light on calls for a manual adjustment ofthe sleeve 64 to vary the spacing of the pawl lever from the strokelever for more or less let oil as required. In a loom at rest, the lighton calls for an increase or decrease of warp tension by means ofmanually rotating the shaft 66.

It is obvious that the mechanisms hereinbefore described and illustratedare subject to wide variations and modifications within the scope of theappended claims.

What is claimed is:

l. A tension unit for the thread from the warp beam of a loom, the unitcomprising two end housings, each end housing comprising spaced parallelside and end members and a top member, the bottom of each housing beingopen and the members being secured along corresponding edges, the sidemembers of each housing having a pair of aligned openings formed thereinadj acent the outer end and a second pair of aligned openings formedtherein adjacent the inner end, the second pair of openings beingequally spaced from and above the first pair, a tension roller shaftrotatably disposed through the first pair of aligned openings in eachhousing, a tension roller for the warp thread from the beam rotatablydisposed on'the shaft, a whip roller forthe warp thread from the tensionroller rotatably disposed between the second pair of aligned open ingsof each housing, means for rotatably mounting the war beam adjacent thewarp end of the loom, means coacting with the shaft of the tensionroller for pivotally securing the end-housings on opposite sides of theloom with the whip roller adjacent the end of the 100111 and the rollersabove and parallel to the warp beam, a flexible tie rod disposed on theinner ends of the housings, means for distributing the forces acting'onthe tie rod to the shaft of the tension roller, means for maintainingthe whip roller under tension against the warp threads, and signal meanscoacting with the shaft of the tension roller to indicate when thepressure of the whip roller against the warp thread exceedspredetermined limits.

2. A tension unit according to claim 1 in which the means coacting withthe shaft of the tension roller for pivotally securing the end housingson opposite sides of the loom with the whip roller adjacent the end ofthe loom and the rollers above and parallel to the warp beam comprises astand for the warp beam and the tension unit, the stand comprisingspaced parallel side members disposed on opposite sides of the loom atthe warp end, means for rotatably securing the warp beam between theside members, at least one bracket adjustably disposed on each sidemember of the stand, the bracket extending upwardly above the sidemember through the open bottom of the corresponding end housing, theupwardly extended end of the bracket having an opening formed thereinfor the rotatable insertion of the shaft of the tension roller.

3. A tension unit according to claim 1 in which the means fordistributing the forces acting on the tie rod to the shaft of thetension roller comprises a rigid compensating brace of U-shape, the endsof the side portions of the U-shape brace being secured to the shaft ofthe tension roller intermediate the end housing and the roller at eachend thereof, the bottom portion of the U- shaped brace being adjacentthe tie rod on the side of the whip roller, and means for pivotallysecuring the bottom portion to the tie rod substantially at the centerof each.

4. A tension unit according to claim 1 in which the signal meanscoacting with the shaft of the tension roller to indicate when thepressure of the whip roller against the warp thread exceedspredetermined limits comprises a control arm disposed on the shaft ofthe tension roller, the arm extending inwardly under the tie rod andthence upwardly, a movable electrical contact disposed on one side ofthe upwardly extended portion of the arm, a second movable electricalcontact transversely and adjustably disposed through the first, astationary contact disposed on the stand and coacting with the movablecontacts, an electric light lamp disposed on the stand, and a normallyopen electric circuit between the contacts and the lamp.

5. In a loom having a full floating whip roller maintained at apredetermined pressure against the warp thread by hydraulic springdeflection against the roller at both ends, the springs being actuatedby the lands of pistons controlled by a hydraulic fluid from a mastercylinder; the improvements comprising a cover for each spring andpiston, the cover having a longitudinal opening formed therein, theopening having a graduated scale along one longitudinal edge, and the 10land of the piston having an index mark coacting with the scale.

6. A positive let on" mechanism for the warp thread from the warp beamof a loom, the beam having a gudgeon, the loom having a strokingmechanism, a tension unit, and stand supporting the tension unit andbeam, and the tension unit having a control arm equipped with a balljoint; the let off mechanism comprising a housing disposed through oneside of the stand, a helical gear bushing rotatably disposed through thehousing at one side of and parallel to the beam, the outer end of thebushing being extended beyond the stand and the housing, a ratchet geardisposed on the outer end of the bushing, and pawl means in operableengagement with the stroking mechanism of the loom for rotating theratchet gear in one direction; the let off mechanism further comprisinga shaft rotatably disposed through the bushing and extended beyond theends thereof, a spur gear keyed to the extended inner end of the shaft,a vertical rack reciprocally disposed in the housing and in operableengagement with the spur gear, and means coacting with the rack and theball joint for varying the spacing of the pawls relative to a tooth ofthe ratchet gear; the let oif mechanism further comprising a worm andhellcal gear shaft rotatably and horizontally disposed through thehousing at a right angle to and in operable engagement with the helicalgear bushing, one end of the worm and helical gear shaft being extendedthrough the housing, and means for manually rotating the extended end;the let-off mechanism further comprising a worm gear for the gudgeon ofthe warp beam in operable engagement with the worm and helical gearshaft, the worm gear having a central circular opening and the openinghaving two spaced slots formed in the rim thereof, and means coactingwith the slots to form a universal joint between the worm gear and thewarp beam.

7. A let off mechanism for the warp threadfrom the warp beam of a loomaccording to claim 6 in which the pawl means in operable engagement withthe stroking mechanism of the loom for rotating the ratchet gear in onedirection comprises in combination an inverted U-shaped stroke lever,one end of the lever being rotatably disposed on the extended outer endof the shaft through the bushing and the other end rotatably disposed onthe extended outer end of the bushing, means intermediate the strokingmechanism of the loom and the outside surface of the inverted bottomportion of the U-shaped lever for reciprocating the lever, a pawl leverof inverted L-shape keyed to the extended outer end of the shaft throughthe bushing, the inverted bottom portion of the L-shaped lever coactingwith the inverted bottom portion of the stroke lever, a plurality ofpawls p-ivotally disposed on the inverted bottom portion of the L-shapedlever, the V pawls being directed toward the warp beam and in operableengagement with the teeth of the ratchet gear, each pawl being ofdifferent length, the length of each pawl following the pawl of greatestlength being shorter than the preceding pawl by a distance equal to thecircular pitch of the ratchet gear divided by the number of pawls.

8. A let olf mechanism for the warp thread from the warp beam of a loomaccording to' claim 6 in which the means coacting with the rack and theball joint for varying the spacing of the pawls relative to a tooth ofthe ratchet gear comprises an adjustable control rod, means forpivotally securing one end of the rod to the top of the rack, theopposite end of the rod being extended upwardly to the control arm andexternally threaded, a sleeve slidably disposed through the ball joint,the bottom of the sleeve having a threaded opening formed therein forthe threaded attachment of the threaded end of the rod, and the top ofthe sleeve having formed thereon a knob coacting with the ball joint.

9. A let off mechanism for the warp thread from the warp beam of a loo-maccording to claim 6 in which the ratchet gear has a pulley formed onthe inner surface thereof, a brake band disposed substantially aroundthe pulley, means for anchoring one end of the brake band to the stand,and means for adjustably anchoring the opposite end to the standadjacent the anchored end.

GEORGE W. KRETZSC'HMAR.

References Cited in the file of this patent UNITED STATES PATENTS Number5 1,705,637 2,305,422 2,398,547 2,398,925 2,450,488 2,507,828 2,565,386

15 Number Name Date Deleu Mar. 19, 1929 Herard, Jr. Dec. 15, 1942 Moessinger Apr. 16, 19h; Darwin Apr. 23, 1946 SGhedin Oct. 5, 1948 Stephensenet al. May 16, 1950 Marcy Aug. 21, 1951 FORETGN PATENTS Country DateGreat Britain s Aug. 12, 1926

